I'll rephrase my estimate of the Soviet reaction to the conflict based on the assumption that Stalin is dead and out of the picture by March 1946, and the USSR is being run by a post-Stalin collective leadership:
The Soviet collective leadership will be cautious, so it will not be encouraging Tito to be aggressive and will be discouraging those tendencies, maybe the Soviet leadership will be reluctant to spend its veto power in the Security Council on Tito's behalf, and Tito uses that as an excuse to back down.
The tools America has at hand to retaliate are primarily Air Force.
From the snippet of the news article, it sounds like the British were not trying to escalate the situation, or take the lead in escalating it. The British are really key here because they occupy the area of Austria adjacent to Yugoslavia, and the Americans don't.
In terms of ground power, Tito has an advantage at the outset. The occupation troops in Germany aren't primed to switch into combat mode, and certainly not to do amphibious ops in the Adriatic. Theoretically, Yugoslavia could use his ground forces to retaliate in the Trieste zone and northeast Italy, or Greece, against being bombed by the Americans, but he would have to know that is highly escalatory and not wanted by Stalin and putting him in US sites, setting him up for a mobilized US-UK-Italian reaction months down the line or an atomic reaction at the end of the day.
Besides bombing and anti-air, the main options Washington and Belgrade have against each other on the ground are funding dirty wars against each other, with the Americans trying to support the fragments of the Ustashe, Chetniks and any other Royalists, and Tito ramping up support for the Greek Communists.
If Yugoslavia gets invaded it knows how to go guerrilla. Despite the US mobilization potential, the Soviet collective leadership watching a US invasion of Yugoslavia really has to consider if he can afford to sit it out and watch, or if it better just go on the offensive to crush western forces in Germany and the continent in general. Regardless of extent, Soviet action might be required to prick the growing American aggression bubble, if it looks like American invaders are intent on regime change in Yugoslavia, with restoration of a Kingdom or breaking up the country.
There's lesser options too, reinforcing Central Europe, aiding Tito's guerrilla resistance, authorizing eastern bloc or Soviet "volunteers" to fight on the side of the Yugoslavs, a la the Korean War. But the Soviet leaders could just decide that is pussyfooting around and do a general all-arms offensive against western and Southern Europe. They will really be trying press for diplomatic solutions and trying to stimulate worldwide peace movements and protests.
Tito being in an escalatory mood seems to me like the kind of thing that will remind Soviet leaders how little they are interested in getting into World War Three right now, and will spur repeated transnational Communist Party contacts with the Yugoslavian Party, to Tito, and all the other Yugoslavs, to try to calm things down. If Tito seems stubborn, they'll ask other Yugoslavs to get him to see reason, and may encourage them to take matters into their own hands. But they won't think they can easily "snap their fingers" and get him replaced on demand. And as much as they don't want to get sucked into war, they don't want Tito's Yugoslavia to lose to the point of outright overthrow of its socialist system----although, they might live with that if the only alternative is getting into war directly. The Soviet bloc states could try to thread the needle of accepting western conquest of Socialist Yugoslavia, or going on the attack conventionally against western invaders, by supplying Yugoslav forces as long as they can maintain first conventional and then partisan resistance.
A US invasion of Yugoslavia in the late 1940s? A successful beat-down and pacification, or a Vietnam in the Vardar?
trove.nla.gov.au
